In a PUCCH format 2b of a Long Term Evolution (LTE), a User Equipment (UE) needs to feed back Channel Status Information (CSI) and Acknowledgement/Negative Acknowledgement (ACK/NACK) information simultaneously. Wherein, with regard to CSI, after the CSI is coded and modulated into 10 symbols, it is carried by adopting 10 Orthogonal Frequency Diversity Multiplexing (OFDM) symbols of two slots; with regard to 2-bit ACK/NACK information, after the 2-bit ACK/NACK information is coded and modulated into one symbol, it is carried by adopting the second reference symbols on the two slots. FIG. 1 is a structural diagram of a PUCCH format 2b in an LTE, and as shown in FIG. 1, blank small squares show carrying the CSI information; small squares with vertical-stripe shadow show carrying reference symbols, and small squares with diagonal shadow show reference symbols carrying the ACK/NACK information.
In the LTE-A, since it introduces technologies such as coordinated multi-point Tx&Rx, carrier aggregation and high order multi-antenna, and so on, the UE needs to feed back a great deal of channel status information, and meanwhile, since uplink multi-antenna is supported in the LTE-A, a PUCCH sending method based on the multi-antenna becomes an issue of concern increasingly.
At present, when the number of uplink antennas is M, a typical sending method of the PUCCH format 2b is: after the CSI is coded and modulated, sending it to a base station through M orthogonal PUCCH resources, wherein each transmitting antenna adopts one orthogonal PUCCH resource. In the PUCCH format 2b based on multiple antennas in the LTE-A, a traditional sending method for the ACK/NACK information is: after the 2-bit ACK/NACK information is modulated by a Quadrature Phase Shift Keying (QPSK) signal, sending it by using repeatedly the second reference symbols on different slots of the PUCCH channel on different antennas. In this method, it is equivalent to coding the 2-bit ACK/NACK information repeatedly to generate 8-bit information and send to the base station; and the minimum Hamming distance is relatively short in the repeated coding, thus the feedback performance of ACK/NACK is limited.
However, in the LTE/LTE-A system, the base station judges whether the sent data is needed to be retransmitted according to the ACK/NACK information fed back by the UE, and if errors occur in the ACK/NACK information fed back, information loss or unnecessary retransmission will be caused and communication quality is seriously influenced.